The present invention relates to a milling cutter. More specifically, the present invention relates to a fastening means to fasten a cartridge to a milling cutter body.
A milling cutter (or face milling cutter) is commonly used in a milling machine. The main function of the milling cutter is to refine the surface of a workpiece and to thereby generate a relatively smooth surface.
A milling cutter has at least one cutting blade. In most of the milling cutter systems, the cutting blade is mounted on a cartridge body, The body of a milling cutter may accommodate a number of cartridges, each of which comprises a cutting blade; the cartridges are provided diametrically in several hollow sections at the outer surface are in the circumferential direction.
The cartridge which holds a cutting blade is mounted on the milling cutter body in several ways. The most common way is to use fastening bolt.
The advantage of the use of cartridge systems is that in the event of wear or damage occurred on the cutting blade, then the damaged cutting blade cap simply be removed and then replaced by the new one, By this principle, the milling cutter body tan still be used, although any of the cutting blades have been changed or replaced repeatedly.
The milling cutter is run by rotating the drive shaft (spindle) at a certain rotation speed with a certain rotation direction and the feeding action is conducted in a certain direction against the material being processed.
The disadvantage of a cartridge system is reduced rigidity of the cutting blade relative to the milling cutter body. In such instance, rigidity is reduced since the cutting blade is a separate part of the milling cutter body and it is joined to the milling cutter body through several other components including cartridge.
A means for joining the cartridge comprising a cutting blade to the body of the milling cutter will greatly influence the rigidity and performance of a cutting blade during in operation. The low rigidity will lead to:
A commonly used joining system for the cartridge to the milling cutter body comprises the use of bolt type fastener wherein the lower surface of the bolt head is perpendicular to the longitudinal direction of the bolt, as illustrated in
In this manner, the fastening bolt can provide a compressive force to only one direction, while the cartridge engages more than one contact surface to the milling cutter body. On the other contact surfaces, there are no active forces that bind the cartridge to the milling cutter body, causing the possibility of vibration on either surface that does not receive such active force. To obtain a high rigidity of a joint between cartridge and milling cutter body, more surface(s) need to receive compressive forces provided by this fastening bolt.
In other cases, as shown in
A method or means is needed for more effective fastening to tighten or fasten the cartridge to the body of the milling cutter, including selection of the type and design of fastener or bolt, in order to obtain maximum rigidity.
In view of the disadvantages commonly found in the prior arts as described above, the present inventor has been trying to find ways to improve the fastening means to get a higher rigidity to the milling cutter entirely.
The present inventor has identified that a certain type of bolt that is screwed into the cartridge at a certain contact angle of bolt-to-cartridge (α), accompanied with a design on the shape of certain aperture in the cartridge body which is in contact with the fastening bolt, unexpectedly results in a better rigidity to the milling cutter.
Accordingly, the inventor has accomplished the work and providing a milling cutter with a higher rigidity that comprises:
In a preferred embodiment, there is provided a fastening means for a milling cutter wherein the fastening bolt mounted to the cartridge has a contact angle of bolt-to-cartridges in the range of between 15 to 70 degrees, preferably between 17 to 55 degrees, and most preferably between 20 to 45 degrees.
In a preferred embodiment, the type of bolt to be used is a fastening bolt having a generally cone-shaped head, wherein the diameter of upper portion of the cone is greater than the diameter of the lower portion thereof.
In a preferred embodiment, there is provided a milling cutter as described above which is further characterized in that the cartridge body has an aperture that is formed in such a shape that allows expansion and/or deformation to occur along the cartridge body during fastening action to give a robust fastening over milling cutter body. In a preferred embodiment, the aperture is oval or oblong in shape that can accommodate the flat portion of the fastening bolt and slope portion of the fastening bolt head. More preferably, the length in horizontal direction of the flat portion of fastening bolt and slope portion of the fastening bolt head are adjusted to obtain optimum compressive forces to the various surfaces of the milling cutter body.
Embodiments disclosed herein are merely illustrative examples. Modifications can be understood by a person skilled in the art to implement a fastening means for cartridge along with cutting blade into the milling cutter body. Type of cartridges that can be fastened to the milling cutter body can be varied and each cartridge can include a wide range of cutting blades depending on the respective special purposes.
Throughout the description and claims of the present invention, by the contact angle of bolt-to-cartridge (α) is meant an angle formed by the horizontal axis of the fastening bolt (i.e. longitudinal direction of the bolt) and the slope of the surface of the head of fastening bolt.
Referring to
The number of hollow sections (14) provided diametrically in a milling cutter body (10) may be two, four, six, eight and so forth depending on the need and capacity of the milling cutter body (10).
Cutting blade (122) in this application can be made of various materials, such as polycrystalline diamond (PCD), tungsten carbide, ceramic-metallic material (cermet), or high speed steel (HSS). Cutting blade has a sharp edge that serves to cut, and have angles of relief at the back side thereof, so there is no friction between the cutting blade and the workpiece, after the cutting process occurs. The detail of cutting blade (122) is not given in the description here since the present invention will focus only to fastening means of the cartridge to milling cutter body (10).
The fastening means of the present invention comprises a fastening bolt (162) having threaded surface along its length and is removably (detachably) mounted to the corresponding threaded holes (820) to fasten the cartridge (12) to the milling cutter body (10) to obtain a high rigidity.
The fastening bolt (162) has a generally cone-shaped head, wherein the diameter of upper portion of the cone is greater than the diameter of the lower portion thereof. The flat trunk portion of the fastening bolt (162) is threaded and the thread ends up at the ramped section entering the head portion of the bolt. The fastening bolt (162) is typically made of an appropriate metal.
Adjusting wedge (16) and adjusting screw (160) serve to make the adjustment of the height of the cartridge in the vertical direction. Adjusting screw (160) can be loosened and moved up and down along the vertical axis, and is tightened in order to obtain an adequate fastening effect to improve the rigidity of the entire system.
Cartridge body (120) has an aperture (124) in such a form that expansion and/or deformation may occur in the cartridge body (120) during fastening to provide a robust fastening over the milling cutter body (10). In a preferred embodiment, the aperture (124) is elongated oval- or oblong-shaped to accommodate the flat portion (840) of fastening bolt (84) and a slope portion (842) of the fastening bolt (84). Such elongated oval or oblong shape of the aperture (124) will allows those parts closest to the point of contact between the fastening bolt (84) and aperture (124) to be deformed and/or expanded in advance of the other parts which are relatively away from the contact point.
Referring to
According to the invention, as illustrated in
In a preferred embodiment, a fastening means for a milling cutter is provided wherein the fastening bolt (84) has a contact angle of bolt-to-cartridge in the range of between 15 to 70 degrees, preferably between 17 to 55 degrees, and most preferably between 20 to 45 degrees.
In such arrangement, the fastening bolt (84) can provide active compressive forces on at least three contact surfaces simultaneously (86, 87, 88) using only one fastening bolt (84) (
Deformation or expansion of the cartridge body (80) is actively promoting axial compressive force of the fastening bolt (84) to both sides of edges (87, 88) of the cartridge body (80) which is in contact with the milling cutter body (10).
The arrangement results in active compressive forces for at least three sides (86, 87, 88) with one fastening bolt (84) only, so that the level of rigidity increases relative to the prior art that is commonly used for joining the cartridge body (80) with the milling) cutter body (10).
The length in horizontal direction of the flat portion (840) of fastening bolt (84) and slope portion (842) of fastening bolt (84) is managed appropriately so as to obtain optimum compressive forces to the various contact surfaces of the milling cutter body (10) when the fastening bolt (84) is tightened.
Number | Date | Country | Kind |
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S-00201608995 | Dec 2016 | ID | national |
Filing Document | Filing Date | Country | Kind |
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PCT/ID2017/000002 | 6/8/2017 | WO | 00 |